questions in physics

1 ) what will happend to the value of resultant when

a ) vector A add to B and they are in the same directions and same magnitude ?
b ) vector A add to B and they are in the opposite directions and equal magnitude ?
c) vector A add to B and they are in the same directions and unequal magnitude ?
d) vector A add to B and they are in the opposite directions and unequal magnitude ?

a = resultant will be sum of two vectos
b= resultant = 0
c=resultant will be sum of two vectos
d=resultant will be sum of two vectos

2 ) a car traveling towards north is suddenly braked . What is the directiom of its accleration ?

.... towards north

3 ) A basball dropped from the roof of ball building. it take 3 seconds to hit the ground . The height of the building is